1. Field of the Invention
The present invention relates to an engine intake control system in which a surge chamber communicating with an air inlet, a first intake passage that has an upstream end portion and a downstream end portion opening in the surge chamber, and a second intake passage that has an upstream end portion opening in the surge chamber so as to oppose the downstream end portion of the first intake passage across a gap and a downstream end portion connected to an intake port of an engine are formed in an intake manifold mounted on the engine, a sleeve-shaped valve body is slidably fitted around one of the opposing end portions, that is, the first intake passage end portion, of the first and second intake passages, the valve body moving between a first position in which the valve body is distanced from the other of the opposing end portions, that is, the second intake passage end portion, and a second position in which the valve body is in contact with the second intake passage end portion, and an actuator is connected to the valve body via a valve operating system for operating the valve body.
2. Description of the Related Art
Such an engine intake control system is already known, as disclosed in Japanese Patent Application Laid-open No. 7-224670.
In such an engine intake control system, since the first intake passage end portion also functions as a guide member for guiding movement of the valve body, in order to guarantee smooth movement of the valve body it is necessary to control a sliding gap therebetween appropriately and high machining precision is required, but since the first intake passage end portion and the valve body have a large diameter, maintaining high machining precision for sliding faces thereof reduces the productivity and gives rise to high cost.